Cylinder locks are known in which a rotary switch is built directly onto a cylinder lock and is used for various purposes, for example, for on-off switching of electrical circuits, step switching, activating operating controls for machines or equipment or groups thereof, for operating shut-off valves, multiway valves, etc., and can only be operated by the insertion of a key which fits the lock and wherein the key can only be removed when the switch has been moved to an engaged position.
However, such cylinder locks can only have a limited number, usually three but generally a maximum of eight, tumblers, whereby, based on the complete rotation of the key or rotor, it is only possible to economically obtain with such switches a maximum of four switch positions angularly separated by 90.degree. because the hole pattern of the tumblers in the stator is multiplied corresponding to the number of key removal positions. In other words, the number of rows of stator bores must be multiplied by this quantity. Thus, these prior art cylinder locks with a plurality of removal positions which, being coaxially assembled with the actual rotary switch as a switch unit (also called "switch cylinders") are often inadequate to provide the flexibility in switching programs which is needed, are not very reliable due to the small number of tumblers which can be used, and, due to the limited number of possible variations, limiting the permutations available, these cannot be used for locking systems. In general, cylinder locks with shims cannot be provided with a plurality of removal positions for the keys because the shims can become displaced, thereby accentuating the disadvantages of the prior structures.
An object of the present invention is to provide a cylinder lock which overcomes the aforementioned disadvantages and which includes a lock having a plurality of removal positions in which the number of locking openings is selected independently of the arrangement and number of tumblers in the cylinder lock.
Briefly described, the invention includes a cylinder lock for a rotary switch of the type having a stationary part and a movable part rotatable to any one of a predetermined number of positions, the lock comprising a stationary housing coupled to the stationary part of the switch, a stator mounted for rotary motion in the housing and coupled to the movable part of the switch, means for restraining the stator against axial motion relative to the housing, a rotor mounted in the stator for rotary motion relative thereto, the rotor having an operating link attached thereto and rotatable therewith and a key slot to permit insertion and removal of a key in any one of a plurality of rotational positions of the rotor, the positions of said key slot providing a visible indication of switch position, tumbler means in the rotor and stator for preventing relative motion therebetween in the absence of a key in the slot, a locking bolt coupled to the link, the stationary housing having means defining a plurality of locking openings corresponding to the number of switch positions for receiving an end of the locking bolt, the locking bolt being transversely movable between a first position in which the bolt engages one of the locking openings in the housing and a second position in which the bolt is disengaged from the openings, said bolt being movable toward the second position by the link upon rotation of the rotor, spring means for urging the bolt toward the first position, the stator being locked against rotation by said bolt when the bolt is in the first position, the stator, rotor and bolt being rotatable relative to the housing when the bolt is in the second position to move the switch to a new position, the number of the locking openings being selectable independently of the number and arrangement of tumbler means in the cylinder lock.